I am just getting started with Hyperledger and am trying to create the following asset in the .cto file
asset Contract identified by contractId {
o String contractId
o Boolean[] services
}
where all instances of Contract will have a "services" array with a fixed length of 9 (i.e. it should be impossible for the user to create a contract with any other length.)
Does anyone know how I could accomplish this?
you should be able to use this regex eg. String myfield regex=/^[0-9]{9}$/ will make sure it must be 9 digits (if its all digits etc etc).
Related
I'm trying to write the derivation expression for the sum of a to many relationship attribute.
I have an item and a group, the item has a price and total price (amount * price).
I want to write an expression for the total price for the group as the sum of its components.
When I build I get the error
error: Misconfigured Property: LAEItemGroup.totalPrice key path
“items.#sum.totalPrice” uses an operator as an intermediate
component
according to the documentation and the WWDC 2019 Making Apps with Core Data it should be possible to get the sum on a to many relationship.
Could someone please help me find the correct syntax or way to do so.
As a work around I tried to write a var that worked in that class as so
#objc
public var totalPrice: Double {
value(forKeyPath: "items.#sum.totalPrice") as? Double ?? 0
}
so why the KeyPath value works but not in the model editor?
I just finished a WWDC Core Data lab with Rishi who helped me with this! You should use sum:(items.totalPrice) instead of the .#sum syntax. The parentheses syntax can also be used for some other functions (e.g. count:(items) (the number of items in the to-many relationship) or max:(items.createdAt) (the date of the most recent item)).
I've now had an opportunity to check. It seems the format used by the model editor is for the aggregate operator to be at the end of the expression (which as you point out, is different from the format used in other expressions):
items.totalPrice.#sum
Use items.totalPrice.#sum as the derived property's expression in Xcode's model editor.
This only looks to work for numeric types though? I have a property maxDate with a derived property expression of
items.createdAt.#max
It compiles but throws an error at runtime:
'NSInvalidArgumentException', reason: 'currently unsupported (too many steps)
Where Date is the data type for createdAt
I have a index named product in elastic-search with field id, name etc..
I want to search products by id or name but my id field is integer and name is a text, I tried following but getting error while searching by name.
error type":"number_format_exception","reason":"For input string:
\"test\""
def self.search_by_name_or_id(query)
__elasticsearch__.search({
query: {
bool: {
must:{
multi_match: {
query: query,
fields: ["id", "name"]
}
}
}
}
})
end
Problem
Exception is clear, that you are trying to search test which is a String in the integer field and elasticsearch is not able to convert test in integer, instead of test if you had search for 10 or 100, then elasticsearch would convert it into integer and would not throw the exception.
Solution
You are trying to mix 2 things here, I am not sure about your design but if your id field can contain pure numbers i.e. integers, then it's not possible to achieve in a single query the way you are doing.
If you can convert your id field to String, then multi_match query would work perfectly fine, otherwise, you need to first check in your application, that search term can be converted to number or not, i.e. 10 or 100 would work fine but test10 or test100 would not and anyway there is no point of searching these terms in id field as it won't be present as its defined as integer in ES and ES would reject documents containing these terms during indexing time only. So based on your application code check you can construct the ES query which may or may not include the id field in multi-match.
I've been trying to make a graph based on a github repo and was thinking how to connect issues with labels. I've tried both as a string and as a list to no avail. Let's say an issue B has the labels with id 10,11 and 01, i would like to link it with labels with identifier 10, 11 and 01. Even when i try something as simple as :
match (i:issues),(l:labels)
where l.identifier in i.labels_id
create (l)-[:labels]->(i)
Yelds no results. Any thoughts?
Aaand i discovered the problem. When i created the list, it was taken as a string, while the identifiers of the labels where integers. Making a conversion to string in the labels identifiers solved it:
match (i:issues),(l:labels)
where l.identifier in toString(i.labels_id)
create (l)-[:labels]->(i)
Is it possible in Neo4j or SDN4 to create/emulate something similar to a PostgreSQL sequence database object?
I need this thread safe functionality in order to be able to ask it for next, unique Long value. I'm going to use this value as a surrogate key for my entities.
UPDATED
I don't want to go with UUID because I have to expose these IDs within my web application url parameters and in case of UUID my urls look awful. I want to go with a plain Long values for IDs like StackOverflow does, for example:
stackoverflow.com/questions/42228501/neo4j-sdn-4-emulate-sequence-objectnot-uuid
This can be done with user procedures and functions. As an example:
package sequence;
import org.neo4j.procedure.*;
import java.util.concurrent.atomic.AtomicInteger;
public class Next {
private static AtomicInteger sequence = new AtomicInteger(0);
#UserFunction
public synchronized Number next() {
return sequence.incrementAndGet();
}
}
The problem of this example is that when the server is restarted the counter will be set to zero.
So it is necessary to keep the last value of the counter. This can be done using these examples:
https://maxdemarzi.com/2015/03/25/triggers-in-neo4j/
https://github.com/neo4j-contrib/neo4j-apoc-procedures/blob/master/src/main/java/apoc/trigger/Trigger.java
No. As far as I'm aware there isn't any similar functionality to sequences or auto increment identifiers in Neo4j. This question has also been asked a few times in the past.
The APOC project might be worth checking out for this though. There seems to be a request to add it.
If your main interest is in having a way to generate unique IDs, and you do not care if the unique IDs are strings, then you should consider using the APOC facilities for generating UUIDs.
There is an APOC function that generates a UUID, apoc.create.uuid. In older versions of APOC, this is a procedure that must be invoked using the CALL syntax. For example, to create and return a single Foo node with a new UUID:
CREATE (f:Foo {uuid: apoc.create.uuid()})
RETURN f;
There is also an APOC procedure, apoc.create.uuids(count), that generates a specified number of UUIDs. For example, to create and return 5 Foo nodes with new UUIDs:
CALL apoc.create.uuids(5) YIELD uuid
CREATE (f:Foo {uuid: uuid})
RETURN f;
The most simplest way in Neo4j is to disable ids reuse and use node Graph ID like sequencer.
https://neo4j.com/docs/operations-manual/current/reference/configuration-settings/
Table A.83. dbms.ids.reuse.types.override
Description: Specified names of id types (comma separated) that should be reused. Currently only 'node' and 'relationship' types are supported.
Valid values: dbms.ids.reuse.types.override is a list separated by "," where items are one of NODE, RELATIONSHIP
Default value: [RELATIONSHIP, NODE]
I have a list of international phone numbers and a List of Country calling codes.
I would like to identify the Country from the numbers but I can't find a fast and elegant way to do it.
Any idea? The only I got is to have an hardcoded check (Eg. "look at the first number, look at the second number: if it's X then check for the third number. If the second number is Y then the Country is Foo", etc.).
I'm using PHP and a DB (MySQL) for the lists, but I think that any pseudocode will help.
Alternatively, you could use a tool like Twilio Lookup.
The CountryCode property is always returned when you make an API request with Lookup.
https://www.twilio.com/docs/api/lookups#lookups-instance-properties
[Disclosure: I work for Twilio]
i was after something similar to this, but i also wanted to determine the region/state - if available. in the end i hacked up something based on a tree of the digits leading digits (spurred on by the description at wikipedia)
my implementation is available as a gist.
I'm currently using an implementation of Google's libphonenumber in Node, which works fairly well. I suppose you could try a PHP implementation, e.g. libphonenumber-for-php.
The hard-coded check can be turned into a decision tree generated automatically from the list of calling codes. Each node of the tree defines the 'current' character, the list of possible following characters (tree nodes) or a country in case it's a terminal node. The root node will be for the leading '+' sign.
The challenge here is that some countries share the same phone country code. E.g. both Canada and the US have phone numbers starting with +1.
I'm using https://github.com/giggsey/libphonenumber-for-php as following:
/**
* Get country
* #param string $phone
* #param string $defaultCountry
* #return string Country code, e.g. 'CA', 'US', 'DE', ...
*/
public static function getCountry($phone, $defaultCountry) {
try {
$PhoneNumberUtil = \libphonenumber\PhoneNumberUtil::getInstance();
$PhoneNumber = $PhoneNumberUtil->parse($phone, $defaultCountry);
$country = $PhoneNumberUtil->getRegionCodeForNumber($PhoneNumber);
return $country;
} catch (\libphonenumber\NumberParseException $e) {
}
return $defaultCountry;
}
You can easily do a simple lookup starting with the first number, then the second, and so on until you find it. This will work correctly because no calling code is a prefix of another code, i.e. the international calling codes form a "prefix code" (the phone system relies on this property).
I'm not good any good at PHP so here is a simple python implementation; hopefully it is easy to follow:
>>> phone_numbers = ["+12345", "+23456", "+34567", "+45678"]
>>> country_codes = { "+1": "USA", "+234": "Nigeria", "+34" : "Spain" }
>>> for number in phone_numbers:
... for i in [2, 3, 4]:
... if number[:i] in country_codes:
... print country_codes[number[:i]]
... break
... else:
... print "Unknown"
...
USA
Nigeria
Spain
Unknown
Essentially you have an associative array between prefixes and countries (which I assume you can easily generate from that Wikipedia article. You try looking up the first digit of the phone number in the associative array. If it's not in the array you try the first two digits, then the first three. If there is no match after three digits then this number doesn't start with a valid international calling code.